linux-kernel - [PATCH v3 4/6] static_call_inline: Provide trampoline address when updating sites

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Date:   Thu,  1 Sep 2022 13:48:23 +0200
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>, sv@...ux.ibm.com,
        bgray@...ux.ibm.com, agust@...x.de, jpoimboe@...nel.org,
        peterz@...radead.org, jbaron@...mai.com, rostedt@...dmis.org,
        ardb@...nel.org, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, dave.hansen@...ux.intel.com, hpa@...or.com
Cc:     Christophe Leroy <christophe.leroy@...roup.eu>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        x86@...nel.org, chenzhongjin@...wei.com
Subject: [PATCH v3 4/6] static_call_inline: Provide trampoline address when updating sites

In preparation of support of inline static calls on powerpc, provide
trampoline address when updating sites, so that when the destination
function is too far for a direct function call, the call site is
patched with a call to the trampoline.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/x86/kernel/static_call.c | 2 +-
 kernel/static_call_inline.c   | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/static_call.c b/arch/x86/kernel/static_call.c
index aaaba85d6d7f..1c0072272214 100644
--- a/arch/x86/kernel/static_call.c
+++ b/arch/x86/kernel/static_call.c
@@ -113,7 +113,7 @@ void arch_static_call_transform(void *site, void *tramp, void *func, bool tail)
 {
 	mutex_lock(&text_mutex);
 
-	if (tramp) {
+	if (tramp && !site) {
 		__static_call_validate(tramp, true, true);
 		__static_call_transform(tramp, __sc_insn(!func, true), func, false);
 	}
diff --git a/kernel/static_call_inline.c b/kernel/static_call_inline.c
index dc5665b62814..b5de9d92fa4e 100644
--- a/kernel/static_call_inline.c
+++ b/kernel/static_call_inline.c
@@ -195,7 +195,7 @@ void __static_call_update(struct static_call_key *key, void *tramp, void *func)
 				continue;
 			}
 
-			arch_static_call_transform(site_addr, NULL, func,
+			arch_static_call_transform(site_addr, tramp, func,
 						   static_call_is_tail(site));
 		}
 	}
-- 
2.37.1